FR2518655A1 - Energy extractor for sea water - has cylinder with open base and pumping ducts carrying flow control valves - Google Patents

Abstract

The wave energy extractor has a cylinder (1) immersed in water carrying an open wall (2) and a floor (3) with a pumping duct (6). This has a flow control valve (4), and the floor also has a discharge conduit (11) with a valve (9) feeding the energy output. The base of the cylinder is movable in one direction (2-2) with the sea level (N), but can be braked in this direction, using a hydrodynamic resistance. The resistance can be developed by floats attached to the base wall.

Description

 The present invention relates to a hydropneumatic bell for capturing the energy of the swell.

 We know of a device of this kind intended to be installed on the surface of the sea, at an altitude (or level) such that the calm sea level is substantially halfway up the skirt of the bell. To take account of the tides, the device can be attached to a barge.

At the bottom of the bell emerge a suction pipe and a discharge pipe each associated with a valve n1 allowing only the desired direction of flow.

These lines communicate with a suction turbine and a discharge turbine respectively. In the event of swell, the water rising in the bell pushes the air trapped under the bell towards the discharge line while the water which then descends causes an expansion of the air bubble and consequently, a suction by the corresponding conduct. In both cases, there is production of mechanical energy by one or the other turbine.

 This device has a low yield in the case of low and medium swells.

 The object of the invention is to produce a hydropneumatic bell having a good yield under all swell conditions.

 According to the invention, the hydropneumatic bell to capture the energy of the swell, comprising a skirt intended to bathe in water at least by a free edge, and a bottom opposite to the aforementioned free edge and from which a suction pipe provided of a suction valve, and a discharge pipe provided with a discharge valve and connected to means for using the mechanical energy of the air, is characterized in that the bottom of the bell is made movable by axial direction relative to mean sea level, the bell further comprising means for slowing down the movements of the bottom of the bell in the axial direction, and means for. practically prevent immersion of the bottom of the bell.

 At the basis of the invention lies the observation that in the case of low and medium swells, the movements of the water in the known bell have a small amplitude relative to the height of the skirt of the bell.

In particular, even at the crest of a wave, the water level remains very far from the bottom of the bell. Thus, variations in water levels due to waves, instead of being fully transmitted as air movements in the turbines, are in large. measurement absorbed by elasticity of the air cushion interposed between the surface of the water and the turbines.

 In the bell according to the invention, which overcomes this drawback, the bottom of the bell has a variable altitude relative to the mean sea level. When the bell is on the rising flank of a wave, the surface of the water compresses the air cushion enclosed under the bell. This tends to raise the bell but this movement is at most very limited, because it is hampered by the weight of the bottom of the bell and especially also by the braking means. The air cushion must therefore be exhausted through the discharge line, with energy production.

 When the water level thus becomes very close to the bottom of the bell, the means for preventing the immersion of the bottom of the bell, which according to the embodiments of the flotation means and / or means for releasing the braking, allow the bottom of the fitter's bell in a more accentuated manner.- Thus, when the bell is at the crest of the wave, its bottom is substantially flush with the water.

 On the falling side of the wave, the bottom of the bell tends to fall back under the effect of sound. own weight. This movement is however restricted by the braking means, so that the descent from the bottom of the bell is lower than the amplitude of the swell.

 As the rise of the bottom of the bell is accentuated when the bottom is on the edge of the water, but that on the other hand the descent of the bottom is practically only a function of the swell period, the altitude of the bottom of the bell s 'always adapts to the state of the sea. If the swell decreases, with each wave less important than the previous ones, the means to prevent the submergence of the bottom act less quickly and the bottom therefore rises to a lower altitude than during from previous waves. If on the contrary the swell increases in amplitude, with each larger wave than the previous ones, the means to prevent the immersion of the bottom act longer and the bottom rises to a higher altitude than during the previous waves. In steady wave conditions, the rise in the bottom of the bell is equal to the fall in each wave.

 Thanks to this automatic adaptation of the altitude of the bottom of the bell, the permanent air cushion between the surface of the water and the turbines is eliminated, and for any swell height, the corresponding air volume is each wave is trapped and expelled through the means of using pressurized air.

 Other features and advantages of the invention will emerge from the description below.

In the appended drawings, given by way of nonlimiting examples:
- Figure 1 is a schematic view in axial section of a first embodiment of the bell, according. to the invention;
- Figure 2 is a more detailed view on an enlarged scale of the bottom of the bell of Figure 1, still in axial section;
- Figures 3 to 8 are views similar to Figure 1, but showing different operating phases of the bell, the latter being respectively on the rising slope of a wave, at the end of this rising slope, at the top of the wave, on the downward slope of the wave, in the hollow of the wave and in calm sea;
- Figure 9 is a view similar to Figure 1 and concerning a second embodiment of the bell according to the invention;
- Figures 10 and 11 are two partial schematic views showing the operation of the bell of Figure 9 at the start and end of the rise in the water level; and
FIGS. 12 to 14 are diagrams showing the operation of the two detectors of the bell of FIG. 9.

 The bell shown in Figures 1 to 8 comprises a cylindrical skirt 1 whose axis Z-Z. is substantially vertical when the bell is in service in the absence of lateral forces The bell 1 is constantly bathed in water at least by its free lower edge 2.

A bottom of the bell 3, substantially circular and planar, welded to the skirt 1, closes the latter at its upper end. The internal volume of the bell, by means of a suction valve 4 and a suction pipe 6, communicates with a suction turbine 7 whose intake manifold 8 communicates with the 'atmosphere.

The interior of the bell is also connected, via a discharge valve 9 and a discharge pipe 11, with a discharge turbi-ne 12 whose exhaust pipe 13 opens into the atmos sphere. Tubing 6 and 11 open into the bottom. 3 of the bell, and the valves 4 and 9 are located at the end of the pipes 6 and 11 adjacent to this bottom 3. The turbine 7 is a low pressure turbine operating from the depressions which may exist inside the bell , while the turbine 12 is a medium pressure turbine operating from the overpressure that may exist in the bell. In the example shown, each turbine 7, 12 is coupled to an electric generator 14, 16 respectively.

 According to the invention, the bottom of the bell 3 and the skirt 1 which is attached to it are made mobile in the axial direction ZZ with respect to the mean level N (FIGS. 3 to 8) of the sea. In the example shown, the bell, which can be moored to a barge, to a quay or to the bottom, in a way allowing this mobility along the ZZ axis, constitutes a body which floats thanks to the air cushion 17 (Figures 3 to 6) trapped between the surface of the water 18 and the bottom of the bell 3.

 The bell further comprises means for braking its movements along the Z-Z axis. In the example shown, these means comprise a hydrodynamic brake 19 consisting of a disc 23 of axis ZZ fixed to the skirt 1 of the bell by means of a tubular column 21 of the same axis, and of spokes 22 welded at column 21 and at skirt 1.

The disc 23 has a certain number of orifices 26 in which the sea water passes with friction when the bell undergoes vertical movements. The disc 23 is sufficiently distant from the edge 2 of the skirt 1, to be in service in an area where the water does not follow the vertical movement of the surface 18.

A rim 24, fixed around the disc 23 and flared on either side of it cooperates with the disc 23 to generate strong movements of water when the bell moves along the axis ~ Z-Z.

 The column 21 is extended beyond the disc 23 and carries at its end a ballast 27 whose center of gravity is on the axis Z-Z.

 The bell further comprises means for practically preventing the immersion of its bottom 3. In the example shown, these means comprise an annular float 34 fixed in the vicinity of the bottom 3, on a cylindrical rim 36 extending the skirt 1 beyond from the bottom 3.

The lower edge of the rim 36 has openings 37 preventing it from forming on the bottom 3 a bowl of water disturbing by its weight the operation of the bell. The float 34 is dimensioned so that the buoyancy suffered by the bell when the float 34 is immersed is greater than the weight tending to be driven.

the bell towards the bottom, even in the absence of the air cushion 17.

 As shown in FIG. 2, the shutter 28 of the discharge valve 9 rigidly carries a pusher 29 directed towards the interior of the bell, and articulated by its free end to one of the ends of a rocker 31 whose l 'other end, located beyond a pivot 32, carries an expanded polystyrene float 33. Of its coAte ,,' the suction valve 4 is a valve of the usual type fia calibration spring.

 The hydropneumatic bell operates as follows, as shown in Figures 3 to 8.

 - When the bell is on the rising side of a wave (Figure 3), the air cushion 17 is compressed by the rise of the surface of the water 18 in the bell. This removal which is exerted on the bottom 3 of the bell, tends to raise it.

However, this movement along the axis Z - Z is of low amplitude, because it is thwarted by the weight of the bell and especially by the hydrodynamic brake 19. The compressed air of the air cushion 17 must therefore be evacuated almost entirely by the discharge valve 9 and the pipe 11, with energy production in the turbine 12. Due to the overpressure in the bell, the level of water 18 in the bell is substantially lower than the water level 38 outside the bell.

 When the water level 18 inside the bell has almost reached the bottom 3, the water level 38 outside the bell reaches the float 34, which accentuates the upward movement of the bell, as schematize the two arrows A in FIG. 4 by comparison with the single arrow A in FIG. 3. However, the air cushion 17, still under overpressure, continues to evacuate via line 11. This certainly allows a rise additional water levels 18 and 38 relative to the bell, but taking into account the aforementioned dimensioning of the float 34, it can hardly be completely submerged. Thus, when the bell is at the crest of the wave (FIG. 5), the float 34 and the bottom 3 are substantially in the water, while the air cushion 17 has practically disappeared. the float 33 is lifted by the water contained in the bell, which causes the shutter 11 of the valve 29 to be forcedly closed. This prevents seawater from passing through the turbine 12.

 The bell then passes over the falling edge of the wave (Figure 6). It tends to follow the descent of levels 18 and 38 under the effect of its own weight. However, the hydrodynamic brake 19 only allows it to descend S symbolized by the arrow D, of low speed compared to that of the level.

The ballast 27 ensures that the axis Z-Z of the device remains substantially vertical. The air cushion 17 recovers in the bell but it is now in slight depression instead of being in overpressure.

Thus, the valve 4 opens and air is sucked through the line 6 with energy production in the turbine 7. When the bell is in the hollow of the wave (Figure 7), it bathes in water over a certain height from its free edge 2. The cycle then returns to the phase of FIG. 3 and so on.
The cycle that we have just described is that which takes place for successive waves of the same height.

The variation in altitude undergone by the bell on the falling edge of the wave is then equal to the total variation in altitude undergone by the bell in the direction of ascent on the rising edge of the wave.

 If the waves decrease in height, the floats 34 dive shorter and less deeply into the water as they approach each wave crest, so that the rise of the bell is less important than the descent. Indeed, the latter which practically depends only on the balance between the weight of the device and the resistance of the brake 19, is substantially constant if the period of the swell is itself constant, which is frequent. , the altitude of the bell measured at each peak of the wave gradually decreases and always tends to take a value such that the situation described with reference to FIG. 5 is achieved.

 If on the contrary, the amplitude of the swell increases, we note that the altitude of the bell measured at each crest of the wave increases progressively, because with each ascent, the float 34 penetrates longer and rains deep below the surface 38. In also this situation, the apparatus always tends to return to the situation of figure 5.

 Another important advantage of the device is that the turbine 12 is protected against excessive overpressures in the pipe 11. Indeed, if the air cushion 17 tends for some reason to become excessively compressed, the bell undergoes an upward movement more accentuated, which tends to avoid excessive overpressure.

This is all the more advantageous as the energy being trapped in the bell is not lost as in the case of a safety valve and will be used later. The apparatus thus ensures, to a certain extent, pressure regulation at the inlet of the turbine 12.

 As shown in FIG. 8, in calm sea, the device floats on its float 34, only a little air remains at the bottom of the bell, and the shutter 9 is kept closed by the float 33.

 The embodiment of FIGS. 9 to 14 is more particularly intended for harnessing, in connection with a barge, the energy of very strong swells, which can range from 5 meters to 15 meters or more in depth of trough. This example will only be described with regard to its differences from that of FIGS. 1 to 8.

 In this example, the bottom 103 of the bell is mounted in leaktight and sliding fashion in a cylindrical sheath 141 of axis Z-Z, intended to be rigidly fixed for example to the vertical side of a barge (not shown).

The part of the sheath 41, located below the bottom 103, constitutes the skirt 101 of the bell.

 Although this is not essential, the bottom 103 is made so as to undergo, when it is reached by the surface 18, an Archimedes thrust at least equal to its own weight and to that of the elements which weigh on it ( at least parts of lines 6 and 11, valves 4 and 9 and other elements described below).

 The bottom 103 has a cylindrical peripheral rim 142 directed towards the free edge 2 of the skirt 101.

To exploit swells with a hollow of 15 m, the edge, 142 can be for example 2 m high. On this rim 142, the bottom 103 carries an annular seal in polytetrafluoroethylene 143 ensuring the seal between the bottom 103 and the sheath 141 which is preferably made of stainless steel.

 The braking means 119 are means ensuring, when in action, the axial immobilization fu the bottom of the bell 103 in the sheath 141. They comprise a hydraulic cylinder whose body 144 is fixed to the barge while the piston 146 is associated with a rod 147 whose external end is attached to the bottom 103. The two chambers 148 and 149 separated in a sealed manner by the piston 146 can communicate with each other by a bypass 151 whose opening and closing is controlled by a solenoid valve 152.

The solenoid valve 152 is itself controlled by the means to substantially prevent the bottom of the
Bell. These include a water presence detector 153 fixed on the internal face of the rim 142 in the immediate vicinity of the bottom 103. The detector 153 ensures the opening of the electro-valve 152 as soon as it is in the presence of water, and closing the solenoid valve 152 as soon as it is no longer in the presence of water.

 The solenoid valve 152 is also controlled by a second water presence detector 154 with timer, fixed on the internal face of the flange 142 at a short distance, approximately 5 to 10 cm, below the detector 153. The detector 154 controls the closing of the solenoid valve 152 as soon as it is in the presence of water, but does not command the opening of the solenoid valve 152 until it has remained out of water for 20 seconds.

The solenoid valve 152 opens as soon as at least one of the detectors 153, 154 controls its opening.
Preferably, provision is made for the opening and closing controls of the solenoid valve 152 by the detector 153, this for the closing control of the solenoid valve 152 by the detector 154, a short time delay, for example half a second. or a second, to avoid erratic operation of the solenoid valve 152 due for example to chop in front of the detectors.

 The hydropneumatic bell which has just been described operates in the following manner, as shown; Figures 10 to 14.

 - We will first admit that the waves have a constant height and that the bottom 103 already has in the sheath 141 the corresponding suitable altitude.

When the water rises in the sheath 141 (FIG. 10), the surface 18 compresses the air cushion against the bottom 103 and the air 17 is evacuated with production of energy in the turbine 12. The seal 143 prevents the leaks between the flange 142 and the sheath 141. The detector 153, which is not in the presence of water, does not control the opening of the solenoid valve 152, and for reasons which will be explained later, the detector 154 neither does it control the opening of the solenoid valve 152. The air cushion 17 is therefore evacuated via line 11 and the turbine 12.

 After a certain time, the surface 18 of the water in the bell exceeds the lower edge 156 of the rim 142. Consequently, the cushion 17 is entirely trapped between the surface 18, the rim 142 and the bottom 103. The seal 143 therefore no longer has to ensure sealing at this stage when the pressure of the cushion 17 becomes greater. Thus, the seal 143 which only ensures being chewed when the pressure in the cushion 17 is relatively low, can be a low pressure seal generating only a low friction on the sheath 141.

 The bottom 103 having automatically adjusted to the desired altitude in a manner which will be described later, when the machine is on the crest of a wave, the surface 18 of the water is between the detectors 153 and 154 Thus, the time delay at 20 seconds of the detector 154 is reset to zero, so that it will not be able to command the opening of the solenoid valve 152 before 20 seconds, which is more than the current periods of the swell which go from 7 to 12 seconds. This is why the detector 154 did not command the opening of the solenoid valve 152 during the rise of the water in the bell.

 As the surface 18 does not reach the detector 153, the latter also does not control the opening of the solenoid valve 152. Thus, the bottom 103 remains at blocked altitude and the water goes back down into the bell with suction d through the turbine 7.

 If the next wave has the same height as that which has just passed, its peak will again come between the detectors 154 and 153, resetting the time delay of the detector 154. Thus, in the event of constant swell, the bottom 103 is immobilized in the sheath 141.

 If the swell decreases, the peak of the next wave (Figure 13) cannot reach the detector 154. Thus, after a certain time, the 20> seconds of delay of the detector 154 come to an end and the detector 154 causes the solenoid valve to open 152. The bottom 103, subjected to its own weight, takes a slow downward movement, while in the jack 119, the oil expelled from the chamber 149 passes into the chamber 148 by bypass 151. This movement, symbolized by the arrow) of Figure 13 stops when the machine, being close to the crate of one of the following waves, the detector 154 is again submerged. The time delay at 20 seconds is then reset to zero and the solenoid valve 152 closed.

 If on the contrary the height of the waves is increasing compared to the situation represented in FIGS. 10 to 12, the crest of the next wave immerses the detector 154, which resets its time delay to zero without effect on the solenoid valve 152, but immerses also the detector 153. This causes the almost immediate opening of the solenoid valve 152, so that the bottom 103, subjected to the pressure in the bell and also thanks to its own buoyancy, undergoes an upward movement symbolized by the arrow A in figure 14.

This movement ceases when the surface of the water 18 * descending into the bell, emerges again the detector 153.

 Where has therefore understood that in this example as in that of FIGS. 1 to 8, the bottom of the bell automatically takes, with respect to the mean sea level N, an altitude such that the air cushion 17 is systematically purged entirely through the turbine 12.

The machine according to the invention therefore makes it possible to have a good yield under all swell conditions.

 Of course, the invention is not limited to the examples described and shown, and numerous modifications can be made to these examples without departing from the scope of the invention.

 Thus, in the embodiment of Figure 9, the bottom of the bell could be secured to the skirt instead of sliding therein.

 Conversely, in the embodiment of Figure 1, one could provide that the skirt of the bell tower is fixed to a support structure, while the bottom to which would be fixed the column 21, would be sliding in the skirt.

 One could combine the detectors with braking of the hydrodynamic type, the detectors having the role of bringing into play or not a reinforcement of the hydrodynamic braking.

 In the embodiment of FIG. 9, it is not essential that the bottom 103 have buoyancy properties. Indeed, since it cannot be covered with water thanks to the sheath 141, it undergoes any upward push anyway when it is subjected to a pressure on its underside.

 In the embodiment of FIG. 1, the float 34 could be eliminated by adjusting the device for blocking the valve 9 so that it is blocked before the surface of the water reaches the bottom 3. Thus, from a certain level of water in the bell, the air cushion 17 would be totally trapped and would itself play the role of float. Another way of eliminating the floats 34 would be to make the rim 36 high enough so that a large quantity of water cannot enter above the bottom 3. The small quantities which nevertheless pass would be discharged through the openings 37.

 In some cases, it may be both economical and technically preferable not to provide a suction turbine 7. Indeed, this creates a pressure drop on the suction which possibly risks reducing the amount of air which can then be discharged by the discharge turbine.

Claims (13)

 1. Hydropneumatic bell to capture the energy of the swell, comprising a skirt (1, 101) intended to bathe in water at least by a free edge (2), this skirt being closed at its end opposite the aforementioned free edge (2) by a bottom (3, 103) from which a suction pipe (6) provided with a suction valve (4), and a discharge pipe (11) provided with a discharge valve (9 ) and connected to means (12) for using the mechanical energy of the air, characterized in that the bottom of the bell (3, 103) is made movable in the axial direction (ZZ) relative to the mean level of the sea (N), the bell further comprising means (19, 119) for braking the movements of the bottom of the bell (3, 103) in the axial direction (ZZ), and means (34, 153, 152) for substantially prevent immersion of the bottom of the bell (3, 103).  2. hydropneumatic bell according to claim 1, characterized in that the means for slowing down the movements of the bottom of the bell (3) comprise an immersed element (23), integral with the bottom of the bell (3), this element ( 23) generating hydrodynamic resistance to movements of the bottom of the bell (3).  3. hydropneumatic bell according to claim 2, characterized in that a ballast (27) is fixed under this hydrodynamic braking element (23).  4. hydropneumatic bell according to one of claims 1 to 3, characterized in that the means for substantially preventing the immersion of the bottom of the bell (3, 103) comprise flotation means (34, 103, 141) arranged near the bottom of the bell (103).  5. Hydropneumatic bell according to one of claims 1 to 4, characterized in that the means for practically preventing the bottom of the bell from being immersed comprise a detector for the presence of water (153), located in the vicinity of the bottom of the bell (103) and integral with it, which controls the release of the braking means (119) when it is reached by the surface of the water.  6. hydropneumatic bell according to claim 5, characterized in that it comprises a second detector of the presence of water (154), integral with the bottom of the bell (103) and placed lower than the first (153), second detector (154) controlling the release of the braking means (119) when it has remained out of the water for a period greater than the usual periods of swell, and the resetting of the braking means ~ (119) when 'it is reached by the surface of the water (18).  7. hydropneumatic bell according to claim 6; characterized in that the braking means (119) are means. ensuring, when in action, the axial immobilization of the bottom of the bell (103) relative to a supporting structure such as a barge or a quay.  8. hydropneumatic bell according to claim 7, characterized in that the braking means (119) comprise a double-acting hydraulic cylinder (144, 146) interposed between the supporting structure and the bottom of the bell (103), two chambers (148, 149) of the jack being connected by an electromagnetic valve (152) controlled by the detectors (153, 154).  9. Hydropneumatic bell according to one of claims 1 to 8, characterized in that the bottom of the bell (3, 103) and the various elements which it carries (1, 6, 11, 19, 21, 27, 146, 147) constitute an assembly designed to undergo an Archimedes thrust at least equal to its own weight, when the bell is filled with water to its bottom (3, 103).  10. Hydropneumatic bell according to one of claims 1 to 9, characterized in that the bottom of the bell (3) is integral with the skirt (1).  11. Hydropneumatic bell according to one of claims 1 to 9, characterized in that the bottom of the bell (103) is slidably mounted in a sheath (141) intended to be fixed to a support structure, and the part of which lying below the bottom (103) constitutes the skirt (101) of the bell.  12. Hydropneumatic bell according to claim 11, characterized in that its bottom (103) has a peripheral rim (142) directed towards the free edge (2) of the skirt (101).  13. Hydropneumatic bell according to one of claims 1 to 12, characterized in that it includes inside its device (29, 31, 32) for blocking the discharge valve (9), this device being controlled by a float (33) so as to close the discharge valve (9) when the surface of the water (18) is very close to the bottom of the bell (3, 103).